Pathobiology of Spontaneous and Experimental Paratuberculosis (S-5 strain) in Goats with Special Reference to Early Lesions
Shoor Vir Singh,
Ashok Kumar Srivastava,
The present study was aimed to diagnose early cases of paratuberculosis in goats by demonstration of Acid Fast Bacteria (AFB) in faecal and tissue samples; isolation of organisms from faecal and tissue samples, enzyme linked immunosorbent assay (ELISA) and patho-morphological lesions in experimental infection using Indian Bison Type biotype strain S-5 of Mycobacterium avium ssp. paratuberculosis (MAP). Faecal samples from 142 goats from various farm herds of North India were subjected to smear (using centrifugation and decontamination) and cultural examinations. Isolation of MAP was performed in all faecal and 74 tissue samples by inoculation on Herrolds Egg Yolk (HEY) medium with or without Mycobactin-J after decontamination with 0.9% Hexadecylpyridinium Chloride (HPC). Experimental study was conducted on 13 young goats (10 infected, 3 controls) where pathogenicity of the strain S-5 was tested by gross and histopathological lesions and plate-ELISA test. Characteristic gross and microscopic lesions were observed at 90 Days Post Infection (DPI) and onwards. Lesions showing infiltration of macrophages with AFB without granuloma formation, simulating lepromatous form of human leprosy and typical granuloma as in tuberculoid form were observed. Positive humoral immune response was observed at 90 DPI onwards showing antibody titer above the cut off value. There was apparent linear correlation between the antibody levels and days post infection. Performance of different diagnostic tests like examination of faecal smear by direct microscopy, faecal culture, scraping smear examination for MAP from tissue, pathomorphology and plate ELISA test had linear relationship among them. Such study ultimately may help the researchers to select the specific series of tests for detection of MAP from clinical samples.
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